Batteries

2009-03-24T09:52:47Z

58.251.170.38:

The tablets use [http://en.wikipedia.org/wiki/Lithium_ion_battery lithium-ion batteries], which have specific requirements for care to maintain optimal battery longevity.

*No memory. "Li-ion batteries do not suffer from the memory effect. They also have a low self-discharge rate of approximately 5% per month, compared with over 30% per month in nickel metal hydride batteries and 10% per month in nickel cadmium batteries."
*Capacity loss is a function of number of full-discharge cycles since manufacturing, and other stress factors, including over-/under-voltage, over-current, and over-/under-temperature. "a battery stored inside a poorly ventilated laptop may be subject to a prolonged exposure to much higher temperatures than 25 °C, which will significantly shorten its life."
*Heat and cold shortens battery lifespan (heat buildup can be reduced with proper ventilation). "a battery stored inside a poorly ventilated laptop may be subject to a prolonged exposure to much higher temperatures than 25 °C, which will significantly shorten its life."
*Heat affects capacity loss during storage. "Different storage temperatures produce different loss results: 6% loss at 0 °C/32 °F, 20% at 25 °C/77 °F, and 35% at 40 °C/104 °F. When stored at 40% charge level, these figures are reduced to 2%, 4%, 15% at 0, 25 and 40 degrees Celsius respectively."
*Voltage range is from 3.0V (discharged) to 4.2V (charged), with 3.7V being nominal.
*Guidelines to extend battery life
**Stay 40-60% charged for storage - around 3.6-3.8V. "Unlike Ni-Cd batteries, lithium-ion batteries should be charged early and often. However, if they are not used for a longer time, they should be brought to a charge level of around 40%. Lithium-ion batteries should never be "deep-cycled" like Ni-Cd batteries"
**Stay cool. "Li-ion batteries should be kept cool. Ideally they are stored in a refrigerator. Aging will take its toll much faster at high temperatures. The high temperatures found in cars cause lithium-ion batteries to degrade rapidly."
*Only buy new batteries when you need them.
[http://www.laptopbatteryshop.co.uk/ laptop battery]
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Batteries